This invention relates to processing food and products for food. In particular, the invention is directed to the kneading of a multiplicity of substantially integral food pieces, for instance, chunks of meat, fruits or cheese wheels or the like.
The prior art of such food processing is described with reference to the massaging and tumbling of chunks of meat, and in this regard the meat products are, for example, cured hams, ham products, bacon bellies, corn beef briskets, or fresh meats, such as, meat beef rounds, roasts, turkey breasts, or other poultry products. Such meats have been subjected to a tumbling or massaging in various kinds of known apparatus.
Cured meat products are normally needle injected with a curing brine prior to mechanical tumbling or massaging at atmospheric pressure, or alternatively under a vacuum. The purpose of tumbling and massaging is to accelerate the curing process, improve distribution of the curing ingredient and to extract the "bind" protein myosin.
The extraction of myosin results in a sticky or tacky meat surface which improves moisture absorbtion and retention and enhances product coherency during processing.
Massaging boneless hams can improve and accelerate the distribution of injected curing brine resulting in a better cure in less time and most importantly, the yield of the ham after cooking is increased by 5% to 7%. Tumbling of beef rounds or turkey breasts results in a condition that permits several pieces to be stuffed in casings or placed in molds for precooking. After chilling, the agglomerated meat can be thinly sliced without falling apart. Tumbling or massaging also results in other benefits such as improving uniformity of color, tenderness, pliability, control of shrinkage, and reduced cooking losses.
Generally, pale, soft meat such as pork and chicken is massaged while dark, firm meat such as beef, mutton and turkey is tumbled. Tumbling involves the result of "impact energy" influences on muscle such as would occur in allowing meat to fall from the upper part of a rotating drum, or striking it with paddles or baffles. Massaging is a less physically vigorous process and involves "frictional energy" resulting from the rubbing of one meat surface on another, or on a smooth surface of a container.
Known apparatus for this massage processing includes vertical paddle massagers which are shown in U.S. Pat. No. 4,038,426 (Jespersen) and U.S. Pat. No. 3,934,860 (Michels). In such vertical paddle massaging, the paddles are suspended from above to engage the product, and the units may be portable and transportable from the brine injector lines to a process area. Unloading of the tanks is accomplished by tipping the entire unit with hydraulically actuated dumpers. Such paddle massagers are not suitable for bone-in ham due to product damage and are used almost exclusively for boneless ham production. Even for such boneless products, the rotating paddles or stirring blades drag products through the mass of the load. This results in the tearing away and separation of pieces from the main chunks.
Vacuum massagers are basically of two kinds. One incorporates a drum or barrel shaped vessel which rotates in a horizontal position on powered rollers. Such a unit is internally equipped with longitudinal or angularly rotated shelves to effect lifting and mixing. The drum is loaded from the top while in a vertical position and then tilted down 90.degree. for tumbling on rollers. Such massagers require considerable labor for loading and unloading. An example of such an arrangement is shown in U.S. Pat. No. 3,880,067 (Hoffman).
The second kind of vacuum massager is of the sort illustrated in U.S. Pat. Nos. 4,029,824 (Langen), 4,036,122 (Langen), and 3,746,316 (Langen). This system involves an elaborate "Y" configuration vessel with one leg of the "Y" detachable. The drum rotates about a central axis to allow the meat to tumble under the vacuum from one chamber to the next. This system usually involves several detachable chambers or round stainless steel meat tubs mounted on wheels which are used as product collection and transportation containers. Food containers are attached to a conveyor system for indexing to the "Y" drum area. Brine injector heads equipped with a pattern of injection needles may be provided in the two permanent chambers. Because of the height from which the chunks of meat fall from chamber to chamber, damage in the sense of bruising the meat occurs. Where injector needles are employed, tearing or shredding of the muscle is additionally caused.
In the prior art of tumblers, it is known to provide atmospheric pressure tumblers which are horizontal drums, conical at each end and equipped with a manually operated door. Internal horizontal shelves effect the necessary lifting of the product. Such tumblers are used primarily for extracting the bind protein myosin in the preparation of precooked sectioned and formed beef products.
Vacuum tumblers incorporate a horizontal drum running on powered rollers and function much like a laundry tumbler in that it tilts to discharge. The product is loaded through a fold-away chute located at the drum center. The chute is pivoted out of the way and a vacuum door is placed over the charging opening during processing.
There are various other devices designed for other purposes that may have been used or tried by the meat processing industry from time to time, such as ribbon blenders employing helical paddles mounted on and rotated by a central shaft in a cylinder that are used in the chemical industry and small tilting drum-type concrete mixers, but insofar as can be determined, none of such devices has been considered satisfactory or successful, since they have not been adopted.
In the field of kneading food pieces and in view of the above limitations and disadvantages of the prior art, there is a need to provide a means for and method of food processing which can provide a gentle low speed rolling or massaging action on the food pieces.
In particular, with the processing of meat it is necessary to minimize bruising of the product and situations where static load conditions can cause tearoffs or separation. Also in regard to the vacuum tumbling or massaging of meat there is also the need to produce high quality meat products which are uniform in cure, bright in color, free of bruises with the entire meat structure intact and dense in mess.
Furthermore, there is a need for a single high productivity meat massager which permits for prompt processing of slaughtered animals, thereby to minimize the time during which muscles contract and rigor mortis sets in. There is thus a need for a masssager which requires less down time during which the curing brine would only penetrate through osmosis.
There is also a need for a processer which can operate both as a massager and a tumbler, and the prior art discloses units which are either only tumblers or massagers. In such a composite unit there is therefore the requirement for slow speed massaging and a higher speed dynamic tumbling where a requisite amount of physical abrasion is desirable.
Additional needs include those of a reduced capital cost, power, and handling requirements, working space and maintenance. It is also desirable to have a processor which is substantially more self-cleaning than existing processors.